#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	float n, s = 0, t = 1;
	for (n = 1; n <= 20; n++)
	{
		t *= n;
		s += t;
	}
	printf("1+2!+...+20!=%f\n", s);
	return 0;
}